Morphology of Flowering Plants Morphology: The study of various external features of the organism is known as morphology.

Adaptation: Any alteration in the structure or function of an organism or any of its part that results from natural selection and by which the organism becomes better fitted to survive and multiply in its environment. Parts of a Flowering Plant:

A flowering plant has a central axis having two components, viz. underground & above-ground. The underground part is known as root system made up of roots & its branches, whereas the above-ground or aerial part is known as shoot system made up of stem & its branches, leaves, flowers & fruits. Flowers are the modified shoots and fruits are the products of flowers. Leaves are the appendages. All distinct plants are referred to as organs which are of two types viz. vegetative (root, stem & leaves) and reproductive (flowers, fruits & their seeds).

The Root:

The root is underground part of the plant and develops from elongation of radicle of the embryo. Various types of root :

Tap root:

◦ Originated from the radicle. ◦ Persistent in dicot plant. E.g. gram, pea , mango

Fibrous root

◦ Originates from the base of the stem. ◦ Large number of roots replaces the primary root. ◦ This type of root found in monocot plant. E.g. wheat, paddy, grass.

Adventitious root

◦ Roots developed from any part of the plant other than radicle. ◦ Found in grass, Monstera and the banyan tree.

Function of root :

Absorption of water and mineral from soil Anchorage of the plant body Storing reserve food material. Synthesis of plant growth regulators.

Regions of root :

Root Cap : The root is covered at the apex by the thimble-like structure which protects the tender apical part.

Region of meristematic activity :

◦ Cells of this region have the capability to divide. ◦ The cells of this region are very small, thin-walled and with dense protoplasm.

Region of elongation :

◦ Cells of this region are elongated and enlarged. Region of Maturation :

◦ This region has differentiated into matured cells. ◦ Some of the epidermal cells of this region form thread-like root hairs, which

absorbs water and minerals from the soil.

Modifications of Root :

Roots are modified for support, storage of food, respiration. For support: Prop roots in banyan tree, stilt roots in maize and sugarcane, clinging

roots For respiration: pneumatophores in Rhizophora (Mangrove). For storage of food: Fusiform (radish); Napiform (turnip, beetroot); Conical (carrot);

Tuberous (sweet potato); Fasciculated (Asparagus) For nitrogen fixation: nodulated roots (leguminous plants) Parasitic adaptations: Haustorial roots (Cuscuta) For climbing: climbing (Pothas) Epiphytic roots: clinging roots for support/attachment and aerial roots containing

velamen tissue for the absorption of moisture from air. Modified roots for food storage:

Conical – Carrot Fusiform – Raddish Napiform – Beetroot

Tuberous – Sweet potato Fasciculated – Asparagus

Roots modified for support:

Prop roots – Banyan Stilt roots – Pandanus Roots modified for respiration:

Pneumatophores – Rhizophora

Roots modified for nitrogen fixation: Haustorial roots/parasitic roots:

Nodulated roots – legumes Cuscuta sp.

Clinging roots/Climbing roots: Epiphytic roots:

Pothas Orchid

The Stem:

The ascending part of the plant axis is called stem. The stem bears branches, leaves, flowers and fruits. The stem develops from the plumule of the embryo. Nodes and internodes are present on the stem. Leaves and branches come out from the nodes. The portion between two consecutive nodes is called internode. The buds on stem can be terminal or axillary. Young stem is usually green in colour and subsequently becomes woody and brown.

Functions of Stem: Bearing branches, leaves, flowers and fruits. Conduction of water and minerals. Green stems also carry out photosynthesis. Food storage, support, protection and vegetative propagation.

Modifications of Stem

Modification for food storage: The underground stems of potato, ginger, turmeric, Colocasia, etc. are modified for food storage. Such modifications are the tools of perenation to tide over unfavourable conditions.

Modifications for climbing: In some plants, stem tendrils develop form axillary buds. These are slender and spirally coiled structures. A tendril helps the plant to climb to a support, e.g. cucumber, pumpkin, grapevine, etc.

Modification for defence: In some plants, the axillary buds are modified into woody,

straight and pointed thorns. Such thorns protect the plant from browsing animals, e.g. Citrus, Bougainvillea.

Modification for photosynthesis: In some plants of arid regions, the stems are modified into flattened or fleshy cylindrical structures. The flattened structure can be seen in Opuntia and the cylindrical structure can be seen in Euphorbia. Such structures contain chlorophyll and photosynthesis happens in them and are known as phylloclades

Modification for vegetative propagation: Stems are modified for vegetative propagation in many plants.

In some plants, the underground stems spread to new areas and give rise to new plants when the older plants die, and are known as runners e.g. grass and strawberry.

In some plants, lateral branches come out from the main axis. These branches arch

downward to touch the ground; after some growth. These branches then give rise to new plants, and are known as stolons e.g. mint and jasmine.

In some aquatic plants, a lateral branch bears a bunch of leaves and a tuft of roots at

nodes. new plants emerge from such nodes & is known as offset e.g. Pistia and Eichhornia.

In some plants, the lateral branches emerge from the basal and underground portion of

the main stem. Such branches grow horizontally beneath the soil and come out upward to

give rise to leafy shoots, they are known as suckers e.g. banana, pineapple and Chrysanthemum.

The Leaf:

A leaf is laterally borne out of the stem. It is usually a flattened structure. The leaf develops at the node. It bears a bud in its axil. The axillary bud subsequently develops into a branch. Leaves originate from shoot apical meristem. They are arranged in acropetal order.

Main parts of leaf are; leaf base, petiole and lamina. The leaf is attached to the stem by the leaf base. It may bear two lateral small leaf-like

structures called stipules. In monocot plants, the leaf base expands to form a sheath. The sheath partially or completely covers the stem.

In some leguminous plants, the leaf base may be swollen. The swollen portion is called the pulvinus.

The petiole helps to hold the leaf blade to light. Petiole is flexible and thus allows the

lamina to flutter in the wind. This helps in bringing fresh air to the leaf surface and has a cooling effect.

The lamina is expanded green portion of leaf. Veins and veinlets are present on the lamina. The arrangement of veins on a leaf is called venation. There are two types of venation, viz. reticulate and parallel.

Reticulate Venation: When the veins and veinlets form a network, this is called reticulate venation. Reticulate venation is usually seen in dicot plants.

Parallel Venation: When the veins are parallel to each other, this is called parallel venation. Parallel venation is usually seen in monocot plants.

Types of Leaves Simple Leaves: When the lamina is entire or when incised; the incisions do not touch the

midrib; then the leaf is called simple leaf, e.g. mango, guava, etc.

Compound Leaves: When the incisions on the lamina reach upto the midrib; breaking it

into a number of leaflets, then the leaf is called compound leaf, e.g. neem.

A simple way to differentiate between compound and simple leaves is to look for the

axillary bud. The bud is always present in case of a leaf but is absent in case of a leaflet. There are two types of compound leaves, which are as follows:

Pinnately Compound Leaf: In this case, a number of leaflets are present on the rachis (common axis). The rachis represents the midrib, e.g. neem.

Palmately Compound Leaf: In this case, the leaflets are attached at a common point; at the tip of petiole, e.g. silk cotton.

Phyllotaxy: The arrangement of leaves on the stem or branch is called phyllotaxy. There are three types of phyllotaxy, which are as follows:

Alternate: In this type of leaf arrangement, a single leaf arises at each node in alternate manner, e.g. China rose, mustard, sunflower, etc.

Opposite: In this type of leaf arrangement, a pair of leaves arise at each node. The leaves lie opposite to each other in this case, e.g. Calotropis, guava, etc.

Whorled: In this type of leaf arrangement, more than two leaves arise at a node, e.g. Alstonia.

Modification of Leaves:

Tendrils: In some plants, leaves are modified into tendrils to assist in climbing, e.g. pea. Spines: In some plants, leaves are modified into spines for defence, e.g. cactus. The leaf

spine in cacti and in some other xerophytes also helps in reducing water loss by preventing transpiration.

Bulb: In some plants, the leaves are modified into bulb for food storage, e.g. garlic and onion.

In Australian acacia, the leaves are small the short-lived. The petioles expanded, become green and synthesize food.

In insectivorous plant leaves are modified to trap insects e.g. pitcher plant, Venus fly trap.

The Inflorescence: Inflorescence is the arrangement of flowers on the floral axis of stem.

A flower is a modified shoot – ◦ Apical meristem changes to floral meristem. ◦ Internodes do not elongate and the axis gets condensed. ◦ The apex produces different kinds of floral appendages laterally at successive

nodes instead of leaves. Racemose : the main axis continues to grow; the flowers are borne laterally in an

acropetal succession. Cymose : the main axis terminates in flower, hence limited to grow. The flowers are

borne in a basipetal order.

The Flower:

The flower is the reproductive unit in the angiosperms. It is meant for sexual reproduction. Atypical flower has four different kinds of whorls arranged successively on the swollen

end of the stalk or pedicel called thalamus or receptacle. The four whorls are:-

◦ Calyx, corolla, Androecium and Gynoecium. Calyx and corolla are accessory organs. Androecium and Gynoecium are reproductive organs. In flower like lily, the calyx and corolla are indistinct and are called perianth. Bisexual: flower having both Androecium and Gynoecium. Also known as

perfect/complete flower Unisexual: flower having either stamens or carpel. Also known as imperfect/incomplete

flower. When both male and female flowers are found on the same plant, they are known as monoecious, whereas found on different plants known as dioecious

Symmetry :

◦ Actinomorphic: radially symmetrical. ◦ Zygomorphic: bilaterally symmetrical. ◦ Asymmetrical: when a flower cannot be divided into two equal half in any

plane.

Pattern of flower :

◦ A flower may be trimerous, tetramerous or pentamerous when the floral appendages are in multiple of 3, 4 or 5 respectively.

◦ Reduced leaf found at the base of the pedicel are called bract. ◦ Flowers which bears bract are said to be bracteates.

Flowers without bract are said to be ebracteate.

Position of floral parts on thalamus : Hypogynous :

◦ Gynoecium occupies the highest position. ◦ Other whorls are present below the Gynoecium. ◦ Ovary is said to be superior. E.g. mustard, China rose and brinjal.

Epigynous : ◦ The thalamus encloses the ovary. ◦ Thalamus fused with ovary. ◦ The other whorl arises above the ovary. ◦ Ovary is inferior. E.g. guava, cucumber, ray florets of sunflower.

Perigynous : ◦ Ovary is said to be half inferior. ◦ The Gynoecium situated in the centre.

◦ Other whorls located on the rim of the thalamus almost at the same level. E.g. plum, Rose, peach.

Parts of a flower :

Calyx :

◦ It is the outermost whorl ◦ Each member called sepals. ◦ Sepals are green leaf like protect the flower in the bud stage. ◦ Gamosepalous: sepals are united. ◦ Polysepalous: sepals are free.

Corolla :

◦ It is the second whorl of a flower. ◦ Each member called petal. ◦ Usually brightly colored to attract insect for pollination. ◦ Polypetalous: petals are free. ◦ Gamopetalous: petals are united or fused.

Aestivation : the mode of arrangement of sepals or petals in the floral bud with respect to the other members of the same whorl is known as aestivation.

◦ Valvate : sepals or petals in a whorl just touch one another at the margin, without overlapping. E.g. Calotropis.

◦ Twisted : one margin of the appendage overlaps that of the next one and so on. E.g. china rose.

◦ Imbricate : the margin of sepals or petals overlap one another but not in any particular direction as in Cassia and gulmohur.

◦ Vexillary : The large petal (standard) overlaps the two lateral petals (wings) which in turn overlap the two smallest anterior petals (keel).

Androecium :

It is the male sex organ of the flower. Composed of stamens. Each stamen consists of a stalk or filament and an anther. Filament attached at the base

of the anther is known as basifixed whereas attached at the back is known as dorsifixed. Each anther is usually bilobed and each lobe has two chambers, pollen sac. Anthers with

single lobe are known as monothecous and those with two lobes are known as dithecous,

Pollen grains are produced inside the pollen sacs. A sterile stamen is called staminode. Epipetalous: stamens attached to the petals. E.g. brinjal. Epiphyllous: stamens attached to the perianth. E.g. lily. Polyandrous: stamens are free. Monoadelphous: stamens united into one bunch or one bundle e.g. China rose. Diadelphous: stamens fused to form two bundles as in pea. Polyadelphous: stamens fused to form more than two bundles as in citrus.

Gynoecium :

It is the female reproductive part of the flower. Members are called carpel. Each carpel has three parts namely stigma, style and ovary. Ovary is the enlarged basal part on which lies the elongated tube, the style. The stigma usually at the tip of the style. Stigma is the receptive surface for pollen grain. Each ovary bears one or more ovules. Ovule attached to a flattened cushion-like placenta in the ovary. When more than one carpel is present they may be:-

◦ Apocarpous: all carpels are free. E.g. rose, lotus ◦ Syncarpous: carpels fused. E.g. Tomato mustard.

After fertilization:- ◦ Ovules develop into seed. ◦ Ovary developed into fruit.

Placentation : arrangement of ovules within the ovary is known as Placentation. Marginal: Placenta forms a ridge along the ventral suture of ovary eg. pea Axile: Margins of carpels fuse to form central axis eg. Hibiscus Parietal: Ovules develop on inner wall of ovary eg. mustard Free central: Ovules borne on central axis, lacking septa eg. chilly Basal: Placenta develops at the base of ovar eg. sunflower/maize

The Fruit:

It is the ripened or matured ovary after fertilization. Parthenocarpic fruits developed from the ovary without fertilization. Generally fruits consist of a wall or pericarp and seeds. Pericarp may be dry or fleshy. Pericarp differentiated into –

◦ Outer epicarp. ◦ Middle mesocarp. ◦ Inner endocarp.

Fruit developed from monocarpellary superior ovary and are one seeded. Such fruit is said to be drupe as in mango and coconut.

Edible part of the mango is mesocarp. Mesocarp of coconut is fibrous.

The Seed:

After fertilization ovules developed into seed. A seed is made of seed coat and embryo. The embryo is made up of

◦ A radicle

◦ An embryonal axis ◦ One or two cotyledons.

Structure of dicotyledonous seed : Outer most covering of seed is seed coat. Seed coat has –

◦ Outer testa ◦ Inner tegmen.

The hilum is a scar on the seed coat, the point of attachment of developing seed with the fruit.

Above the hilum is a small pore called the micropyle. Embryo present inside the seed coat, consists of -

◦ An embryonal axis. ◦ Two cotyledons

Cotyledons are fleshy and store reserve food. At the two end of embryonal axis are present the radicle and the plumule. In some seed endosperm store the reserve food as in castor. Mature seed without endosperm called non-albuminous seed or non-endospermous as

in bean, gram and pea.

Structure of monocotyledonous Seed :

Generally monocotyledonous seeds are endospermic, orchids are non-endospermic. In seeds of cereals such as maize, the seed coat is fused with the fruit wall. The outer covering of separates the embryo by a proteinous layer called aleurone layer. Embryo is small and located one side of the endosperm and consists of

One large shield shaped cotyledon known as scutellum. A short axis with radicle and plumule. Plumule covered by a sheath called coleoptile. Radicle covered by a sheath called coleorhiza.

Semi-technical description of flowering plants: Various morphological features are used to describe a flowering plant. The description has to be brief, in a simple and scientific language and presented in a

proper sequence. The plant is described beginning with its habit, vegetative characters – roots, stem and

leaves and then floral characters inflorescence and flower parts. After describing various parts of plant, a floral diagram and a floral formula are

presented. The floral formula is represented by some symbols. In the floral formula, Br stands for bracteate K stands for calyx , C for corolla, P for

perianth, A for androecium and G for Gynoecium, G for superior ovary and G for inferior ovary, for male, for female , for bisexual plants, ⊕ for actinomorphic and % for zygomorphic nature of flower.

Fusion is indicated by enclosing the figure within bracket and adhesion by a line drawn above the symbols of the floral parts.

A floral diagram provides information about the number of parts of a flower, their arrangement and the relation they have with one another.

The position of the mother axis with respect to the flower is represented by a dot on the top of the floral diagram.

Calyx, corolla, androecium and gynoecium are drawn in successive whorls, calyx being the outermost and the gynoecium being in the centre.

Floral formula also shows cohesion and adhesion within parts of whorls and in between whorls. The floral diagram and floral formula in Figure represents the mustard plant (Family: Brassicaceae).

Description of Some important Families: Family: Fabaceae This family was earlier called Papilonoideae, a subfamily of family Leguminosae. It is distributed all over the world. Vegetative Characters: Habit: Mostly herbs and shrubs, trees are also common. Some are climbers (Pisum,

Lathyrus). Root: Branched taproot, usually with nodules containing bacteria of genus Rhizobium. Stem: Herbaceous or woody, branched. Leaf: Simple or compound, alternate, stipulate, leaf base is pulvinate.

Floral Characters: Inflorescence: Racemose, simple or compound. Flower:Bracteate, zygomorphic, bisexual,pedicellate, heterochlamydeous, pentamerous,

hypogynous. Calyx: Sepals 5, gamosepalous, hairy, valvate or imbricate aestivation. Corolla: Petals 5, polypetalous, papillionaceous, with a standard (vexillum) petal, two

wing petals (Alae) and two keel petals (carinae). Vexillary aestivation. Androecium: Stamens 10, monadelphous or diadelphous, anthers dithecous. Gynoecium: Monocarpellary, unilocular with ovules on marginal placentation. Ovary

superior. Fruit: A legume or lomentum. Seed: Large, Non-endospermic

Economic importance : Many plants belonging to the family are sources of pulses (gram, arhar, sem, moong,

soyabean; edible oil (soyabean, groundnut); dye (indigofera); fibres (sunhemp); fodder (Sesbania, Trifolium), ornamentals (lupin, sweet pea); medicine (muliathi).

Botanical Names of important plants: Cajanus cajan – pigeon pea/red gram/thur dhal Cicer arietinum – chick pea/bengal gram/channa Pisum sativum – pea Glycine max – soya bean Phaseolus mungo (Vigna mungo) – black gram Phaseolus radiatus (Vignaradiata) – green gram Dolichos lablab syn. Lablab purpureus – avare kalu Phaseolus vulgaris – french bean (hulli kayi) Vicia faba – broad bean (Chapparadavare) Cyamopsis tetragonoloba – cluster bean Arachis hypogea – groundnut Trigonella foenum-graecum – fenugreek/methi Macrotyloma uniflorum – horse gram (huruli) Vigna unguiculata – cow pea (alasande)

Floral Formula: Br ٪ K(5) C1+2+(2) A(9)+1 G1

Family: Solanaceae Solanaceae is commonly called as 'Brinjal family‘ or ‘Potato family’. It includes about 90 genera and 2000 species. Members have a cosmopolitan distribution. There are around 60 species found in India. Vegetative Characters: Habit: Mostly annual herbs (Solanum nigrum), undershrubs (Solanum melongena).

Some are shrubs (Solanum torvum) rarely trees (Solanum grandiflorum) and climbers (Solanum seaforthianum).:

Root: Taproot, branched. Stem: Herbaceous or woody, branched, often with prickles. Leaf: Simple, alternate, sometimes pinnately divided into unequal lobes, exstipulate.

Floral Characters: Inflorescence: Cymose. Often solitary cyme. Flower: Ebracteate, actinomorphic, bisexual, pedicellate, heterochlamydeous,

hypogynous. Calyx: Sepals 5, gamosepalous, persistent (in the fruit condition also) valvate aestivation. Corolla: Petals 5, gamopetalous, rotate or companulate or bilabiate (Schizanthus) or

infundibuliform (Datura). Twisted or valvate aestivation. Androecium: Stamens 5, epipetalous. Gynoecium: Bicarpellary, syncarpous, bilocular or tetralocular due to pseudoseptum.

Many ovules on axile placentation. Ovary superior, Obliquely placed. Fruit: Berry or capsule. Seed: Endospermic.

Economic importance: Many plants belonging to this family are source of food (tomato, brinjal, potato), spice (chilli); medicine (belladonna, ashwagandha); fumigatory (tobacco); ornamentals (petunia).

Botanical Names of important plants:

Solanum tuberosum (Potato) is used as vegetable. Solanum melongena (Brinjal/egg plant) is used in vegetable. Solanum nigrum is used in medicine. Capsicum frutescens (Simla Mirch) Capsicum annum (Chilly) Lycopersicum esculatum (Tomato) is used as vegetable (avagode-hannu) Nicotiana tobacum (Tobacco) the leaves of plant are used as tobacco. Datura alba (Dhatura) seed are narcotic and poisonous. Petunia alba is ornamental plant. Cestrum nocturnum (Rat ki Rani) ornamental plant. Atropa belladona medicinal plant Withania somnifera (Aswagandha) medicinal plant

Family: Liliaceae Vegetative Characters: It is commonly called Lily family. It includes about 250 genera and 3700 species that have a cosmopolitan distribution. Around 200 species are available in India. Habit: Mostly perennial herbs, stem often modified into bulbs or corms, rarely shrubs

and trees (Dracenea, Yucca). Some are climbers (Gloriosa, Smilax). Many are xerophytes (Aloe, Agave and Asparagus).

Root: Adventitious, fibrous, sometimes tuberose. Stem: Erect or climbing, branched or unbranched herbaceous, may be modified as

phylloclade (Ruscus) or cladode (Asparagus) or bulb (Alium) Leaf: Radical or cauline, simple or rarely compound well developed or reduced to

sheaths or scales, tubular. Venation is parallel and reticulate in Smilax. Floral Characters: Inflorescence: Variable, mostly racemose, simple raceme or spike or umbel or panicle.

Sometimes solitary cyme (tulips). Flower: Bracteate, actinomorphic, bisexual, pedicellate, homochlamydeous, trimerous,

hypogynous, incomplete in some as they are unisexual (Smilax & Ruscus) Perianth: Tepals 6, in two whorls, polyphyllous or gamophyllous, imbricate or valvate

aestivation. Androecium: Stamens 6, in two whorls of three each usually free or attached to tepals

(epiphyllous) anthers dithecous, usually versatile, introse or extrose. Gynoecium: Carpels 3 (tricarpellary), syncarpous, trilocular, two ovules in each locule

attached on axile placentation, style simple, stigma trifid, and ovary superior. Fruit: Berry or capsule. Seed: Small, endospermic.

Economic importance: Many plants belonging to this family are good ornamentals (tulip, Gloriosa), source of medicine (Aloe), vegetables (Asparagus), and colchicine (Colchicum autumnale). Botanical Names of important plants:

Alium cepa (onion) Asparagus racemosus - roots edible, medicinal also Alium sativum (garlic) - medicinal use also Aloe vera extract from the plant used as a purgative and for treating liver disorders. Crinum latifolium (Sukh darshan plant; pink striped trumphet lily) medicinal plant Crinum asiaticum (spider lily) for urinary problems Smilax zeylanica for curing arthritis Dracaena termiflora Lilium candidum Gloriosa superba (glory lily; tiger’s claw) a fencing plant Yucca filamentosa

Botanical Names of important plants:

Alium cepa (onion) Asparagus racemosus - roots edible, medicinal also Alium sativum (garlic) - medicinal use also Aloe vera extract from the plant used as a purgative and for treating liver disorders. Crinum latifolium (Sukh darshan plant) Crinum asiaticum for urinary problems Smilax zeylanica for curing arthritis Dracaena termiflora Lilium candidum Gloriosa superba (glory lily) a fencing plant Yucca filamentosa